The advanced detection primarily means to detect the presence or absence of harmful geological formations or water-rich bodies and water-conducting channels in the head direction of tunnel, roadway and working face driving by direct or indirect way, so as to provide detailed detection information for security of tunnel driving.
The direct method currently used for coal mine advanced detection is drilling method and the indirect method is geophysical prospecting method. Although the drilling method can obtain quite reliable drilling results, the longer construction period and higher costs will affect the normal production of the tunnel and roadway.
The geophysical prospecting methods available for advanced detection now are three-pole method, mine transient electromagnetic method, seismic wave method, borehole electrical method and borehole electromagnetic method after drilling.
These geophysical prospecting methods are carried out in the tunnel, roadway, working face or borehole after drilling. However, for those prior art methods, there are obvious interference of roadway and working face, for example, the detecting results of three-pole method and mine transient electromagnetic method can be affected seriously by the metal apparatus in the roadway and tunnel such as boring machine, rail track, I-beam support, bolts support, transport belt brackets. In addition, the construction design on the site, data observations and the results of the analysis are complex, and it is difficult for overcome the problem of multiple solutions due to using single detecting parameter—resistivity. If using a combination of above-mentioned methods, the costs for advanced forecast will be greatly increased. Furthermore, a disadvantage of those borehole detecting methods after drilled is that the detection of borehole usually cannot be achieved because the borehole often collapses after drilling due to relatively soft coal seam. The seismic method is mainly to solve the problem of geological tectonic interface and cannot explain the rich-water configuration.